What happens if the lateral geniculate nucleus is damaged?

In humans and other primates, visual information is transmitted from the retina to a part of the brain called the lateral geniculate nucleus (LGN), before reaching the primary visual cortex (V1). If the V1 is damaged, conscious vision is lost in the area of the visual field that corresponds to the damage.

Where is the LGN located?

Optic nerve fibres from the eyes terminate at two bodies in the thalamus (a structure in the middle of the brain) known as the Lateral Geniculate Nuclei (or LGN for short). One LGN lies in the left hemisphere and the other lies in the right hemisphere.

What is the MGN?

Anatomical terms of neuroanatomy. The medial geniculate nucleus (MGN) or medial geniculate body (MGB) is part of the auditory thalamus and represents the thalamic relay between the inferior colliculus (IC) and the auditory cortex (AC).

What is the effect of a lesion in the left optic tract?

Lesions in the optic tract correspond to visual field loss on the left or right half of the vertical midline, also known as homonymous hemianopsia. A lesion in the left optic tract will cause right-sided homonymous hemianopsia, while a lesion in the right optic tract will cause left-sided homonymous hemianopsia.

What effect would a lesion in the right optic nerve have on vision?

A lesion of the right optic nerve causes a total loss of vision in the right eye; it also produces a right afferent pupil deficit.

What cells are in the lateral geniculate nucleus?

It is a small, ovoid, ventral projection of the thalamus where the thalamus connects with the optic nerve. There are two LGNs, one on the left and another on the right side of the thalamus. In humans, both LGNs have six layers of neurons (grey matter) alternating with optic fibers (white matter).

What is lateral geniculate nucleus made of?

The LGN consists of six eye-specific layers, four of which receive inputs from parvocellular retinal ganglion cells, and two of which receive magnocellular inputs. Each layer is organized into a precise retinotopic map.

Is the LGN in the occipital lobe?

The LGN neurons (4° visual afferents) send their axons in the internal capsule to the occipital lobe where they terminate in the striate cortex (Figure 15.5). The LGN axons fan out as the optic radiations of the internal capsule and travel through the temporal, parietal and occipital lobes.

What do LGN cells respond to?

Simple Cells are V1 neurons that respond to stimuli with particular orientations to objects within their receptive field. Like cells in the lateral geniculate nucleus (LGN), they have clear excitatory and inhibitory regions.

Which special sense is associated with the lateral geniculate nucleus of the thalamus?

visual perception
the lateral geniculate nucleus of the thalamus – for visual perception; the superior colliculus of the midbrain – for control of eye movements; the pretectum of the midbrain – for control of the pupillary light reflex; and.

What is auditory thalamus?

The auditory thalamus, or medial geniculate body (MGB), is an obligate auditory brain center in a unique position to gate the percept of sound as it projects to auditory cortex and to limbic structures. Both areas are thought to be involved in those individuals most impacted by tinnitus.